the world's longest sperm belongs to the fruit fly Drosophila bifurca. it is 20 times longer than its own body and 10,000 times longer than a human sperm. why does a sperm need to be so long if quantity matters more than quality? according to Scott Pitnick, "giant sperm tails represent the cellular, postcopulatory equivalent of peacocks tails, having evolved through female sperm choice." more sex facts can be found in World Sexual Records.